Donotcall.gov is useless. I pay for Nomorobo on my Verizon iPhone. (I get it free on my landline.) It doesn't catch all the robocallers, but I report the ones that get through.
I just got a new one, though. A no-name, no-number caller rang me and when I answered, she said, "Who are you?" I said, "No, who are you? You called me!" She claimed that someone had called her from my number. I didn't do it.
I get so many spoofed calls that I'm wondering if this person got a spoofed call from my number. Most of the time, when I get a call that looks like a local call, I call it back, and most of those spoofed numbers are disconnected numbers. I hope the robocallers aren't using live numbers now!